以下代码示例的输出是：

{1–e = e2，2–e1 = e1}

package com.sid.practice;

import java.util.HashMap;

import java.util.Map;

public class InputOutputPractice

{

public InputOutputPractice()

{

}

public static void main(String[] args)

{

Employee e = new InputOutputPractice().new Employee(1, "e");

Employee e1 = new InputOutputPractice().new Employee(2, "e1");

Employee e2 = new InputOutputPractice().new Employee(1, "e2");

Map m = new HashMap();

m.put(e, "e");

m.put(e1, "e1");

m.put(e2, "e2");

System.out.println(m);

}

class Employee

{

public Employee(int id, String name)

{

this.id=id;

this.name = name;

}

private int id;

private String name;

public String getName()

{

return name;

}

public void setName(String name)

{

this.name = name;

}

public int getId()

{

return id;

}

public void setId(int id)

{

this.id = id;

}

@Override

public boolean equals(Object obj)

{

return ((Employee)obj).getId()==(this.getId());

}

@Override

public int hashCode()

{

return Integer.valueOf(getId()).hashCode();

}

@Override

public String toString()

{

return this.id + "--" + this.name;

}

}

}

我不明白对象如何e2能够覆盖对象中的键e，但不能覆盖值。以我的理解，输出应该是：

{1–e2 = e2，2–e1 = e1}